Coupling for electrical connector or the like

ABSTRACT

An electrical connector that includes a plug and receptacle which are held together by a bayonet coupling that includes pins on the receptacle which enter grooves in a rotatable but axially fixed coupling ring around the plug shell, the bayonet grooves including inner portions that fall within a radial plane and have no forwardly inclined recesses at their inner ends. A detent to prevent inadvertent rotation of the coupling ring after the connector has been mated is provided by a leaf spring which is carried by the plug shell and has an outwardly projecting portion adapted to enter a recess in the inner wall of the coupling ring.

United States Patent 1 1 Clark 1 1 COUPLING FOR ELECTRICAL CONNECTOR OR THE LIKE [75] Inventor: Kenneth M. Clark, Beaumont, Calif.

[73] Assignee: The Deutsch Company Electronic Components Division, Banning, Calif.

22 Filed: Dec. 26, 1973 211 App]. No.: 427,801

Related U.S. Application Data [52] U.S. Cl. 339/90 R; 339/DIG. 2 [51] Int. Cl. H011 13/54 [58] Field of Search 4. 339/89, 90, 187, 188, 189,

339/DIG. 2

[56] References Cited UNITED STATES PATENTS 3,017,603 1/1962 Bac 339/90 R 3,327,282 6/1967 Krolak 3,393,927 7/1968 Kelly et al 339/90 R FOREIGN PATENTS OR APPLICATIONS 1,157,282 11/1963 Germany 339/DIG. 2

[4 1 July 1,1975

832,515 4/1960 United Kingdom 339/89 M 1,297,925 5/1962 France 339/DlG 2 1,138,364 1/1969 United Kingdom 339IDIG, 2

OTHER PUBLICATIONS IBM Bulletin, Panaro, M.C., Clicking Connector, 12-1958, Vol. 1, No. 4, page 15.

Primary Examiner.loseph H. McGlynn Attorney, Agent, or FirmGausewitz, Carr & Rothenberg [57] ABSTRACT An electrical connector that includes a plug and receptacle which are held together by a bayonet coupling that includes pins on the receptacle which enter grooves in a rotatable but axially fixed coupling ring around the plug shell, the bayonet grooves including inner portions that fall within a radial plane and have no forwardly inclined recesses at their inner ends. A detent to prevent inadvertent rotation of the coupling ring after the connector has been mated is provided by a leaf spring which is carried by the plug shell and has an outwardly projecting portion adapted to enter a recess in the inner wall of the coupling ring.

1 Claim, 24 Drawing Figures COUPLING FOR ELECTRICAL CONNECTOR OR THE LIKE REFERENCE TO RELATED APPLICATIONS This application is a continuation of patent application Ser. No. 347,821, filed Apr. 4, 1973, now abandoned, for Coupling for Electrical Connector or the Like, which is a division of application Ser. No. 167,317, field July 29, 1971, for Electrical Connector (now U.S. Pat. No. 3,727,172), which is a continuation-in-part of application Ser. No. 83,782, filed Oct. 26, 1970, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to electrical connectors.

2. Description of the Prior Art Electrical connectors conventionally include a plug and receptacle. In order to secure the plug and receptacle of the connector together, a bayonet coupling mechanism frequently is used. This may include pins projecting radially outwardly from the shell of one of the sections of the connector, which are adapted to enter grooves in a coupling ring provided on the other section of the connector. The grooves have entrance portions at the forward end of the coupling ring, from which the grooves extend inwardly, terminating in recesses that extend back toward the forward end of the coupling ring. The pins enter the bayonet grooves as the connector is moved toward the mated position, moving to the inner ends of the grooves as the coupling ring is rotated. The coupling ring is engaged by a spring biasing it axially so that the bayonet pins are moved into the recesses at the ends of the bayonet grooves upon the termination of the rotation of the coupling ring. The spring force holding the pins on the recesses acts as a detent that retains the coupling ring against inadvertent rotation.

This arrangement means that the plug and receptacle are moved toward each other a distance beyond their normal mated position before the pins are allowed to enter the recesses at the ends of the bayonet grooves. As the pins are moved into the recesses, there is a slight separational movement of the connector plug and receptacle. Also, it is possible for the coupling ring detent spring to be overcome by an outward pull on the two sections of the connector. This can allow some separation of the plug and receptacle so that the contacts move relative to each other toward an unmated position. Therefore, in order to assure electrical continuity through the connector under all conditions, the pin and socket contacts must be made sufficiently long to permit some relative movement between them without causing disengagement. Consequently, the connector must be made large enough to accommodate the longer contacts, despite continued requirements for reduction in the size and weight of electrical connectors.

SUMMARY OF THE INVENTION The present invention provides an improved electrical connector which overcomes the difficulties outlined above. In this connector, the coupling mechanism provides a secure bayonet connection, but does not depend upon the bayonet pins and grooves to provide the detent that holds the coupling ring against inadvertent rotation. Instead, there is a separate detent for this purpose. Consequently, the grooves in the coupling ring are made circumferential in their inner portions, falling entirely in a radial plane and with no recesses at their inner ends for receiving the bayonet pins. Thus, when the coupling is moved to its mated position, the maximum relative axial movement of the plug and receptacle takes place as the bayonet pins enter the inner groove portions. Also, the coupling ring is axially fixed relative to the plug shell, unlike prior designs in which the coupling ring could be moved by overcoming a spring force. Once the connector has been coupled, the plug and receptacle are permitted no relative movement, so that outward forces on the connector sections cannot cause separation of the pins and sockets. Hence, the pins and sockets may be made quite short because there is no overtravel as the connector is mated, nor will the contacts be moved apart once the coupling has been engaged. This allows the connector to be made smaller and lighter than prior designs.

With no spring in the coupling mechanism, tolerances must be controlled so that the insert faces engage with a proper amount of compression. For the plug, a spacer washer is used to position the coupling ring axially so that the forward edge of the bayonet groove is a predetermined distance from the forward face of the plug insert. Measurements are taken so that a washer of proper thickness may be selected to accomplish the correct spacing between the groove and the insert. For the receptacle, the distance between the opening for the bayonet pin and the forward face of the receptacle insert is measured. Then, a bayonet pin is selected of a diameter such that its rearward surface is a predetermined distance from the forward surface of the insert.

The detent for the coupling ring is provided by a leaf spring which is held by the plug shell and has a central portion which is adapted to enter a recess in the inner circumferential surface of the coupling ring. This occurs when the coupling ring has been rotated to where the bayonet pins are properly positioned at the inner ends of the grooves. The spring is cammed out of the recess for reverse movement in the unmating of the connector.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of an electrical connector made in accordance with this invention;

FIG. 2 is an exploded perspective view of certain portions of the connector, including in particular the parts used for coupling the plug and receptacle;

FIG. 3 is an enlarged longitudinal sectional view of the connector in the mated position;

FIG. 4 is an exploded perspective view, partially broken away, of the plug insert and shell;

FIG. 5 is a transverse sectional view taken along line 55 of FIG. 3;

FIG. 6 is a transverse sectional view taken along line 6-6 of FIG. 3;

FIG. 7 is a fragmentary sectional view taken along line 7-7 of FIG. 5;

FIG. 8 is a fragmentary enlarged perspective view of one portion of the plug insert assembly, illustrating the contact retention fingers;

FIG. 9 is a fragmentary transverse sectional view taken along line 99 of FIG. 3;

FIG. 10 is an enlarged fragmentary view illustrating the details of the finger shape and its engagement with the contact;

FIG. 11 is a fragmentary longitudinal sectional view showing the retention finger spaced from the contact shoulder when the contact is shifted forwardly;

FIGv I2 is a further enlarged fragmentary view illustrating the engagement between the retention finger and the contact shoulder. with the contact under rearward load;

FIG. 13 is an enlarged fragmentary longitudinal sectional view of the forward portions of the inserts of the plug and receptacle. shown slightly separated and illustrating the sealing arrangement for the openings;

FIG. 14 is a fragmentary flat pattern of the inside of the coupling ring. showing one of the bayonet grooves;

FIGv 15 is an enlarged fragmentary sectional view taken along line l5l5 of FIG. 3, illustrating the engagement of the spring tab on the snap ring and the forward end of the receptacle shell;

FIG. 16 is a fragmentary longitudinal sectional view of the connector incorporating one size of bayonet pin and spacer washer used in adjusting tolerances to assure proper engagement at the forward surfaces of the connector inserts;

FIG. 17 is a view similar to FIG. 16, but with different sizes of bayonet pin and spacer washer;

FIG. 18 is a fragmentary longitudinal sectional view of the plug showing the critical dimension between the edge of the bayonet groove and the forward face of the insert;

FIG. 19 is an enlarged fragmentary sectional view showing how the spacer washer controls the dimension between the edge of the bayonet groove and the insert face in different tolerance conditions;

FIG. 20 is a fragmentary transverse sectional view of a group of three different sized spacer washers. one of which is to be selected in properly spacing the forward edge of the bayonet groove;

FIG. 21 is a fragmentary longitudinal sectional view of the receptacle illustrating the manner of measuring to obtain the dimension from the opening for the bayonet pin to the forward face of the insert;

FIG. 22 is a side elevational view of two bayonet pins having outer ends of different sizes;

FIG. 23 is a fragmentary longitudinal sectional view of the receptacle shell and bayonet pin showing how different sizes of bayonet pins may be used in different situations to in both cases position the rearward edge of the pin at the same location; and

FIG. 24 is a fragmentary elevational view of the re ceptacle shell and bayonet pin of FIG. 23.

DESCRIPTION OF THE PREFERRED EMBODIMENT Illustrated in the drawing is a multiple pin and socket connector that includes a plug 9 and a receptacle 10. The general arrangement for retaining the contacts is the same in the plug and receptacle. In the embodiment illustrated. the pin contacts are in the plug and the socket contacts in the receptacle, although this may be reversed if desired. The plug 9 includes a plug shell 11, which is a generally tubular metal member of circular cross section. Within the shell 11 is an insert assembly 12 that serves to retain and hold a plurality of pin contacts 13. The insert assembly 12 includes disks l4 and 15 of a substantially rigid plastic. A suitable material for these members. because of its strength and temperature resistance, is a poiyarylsulfone marketed under the trademark AstreF 360 plastic by Chemical Division, 3M Company, 3M Center. St. Paul, Minn. The disks 14 and 15 are suitably bonded together at their mating radial faces. At the forward end of the insert assembly 12 is bonded a gasket disk 16 of a resilient elastomeric material. such as silicone rubber.

The insert assembly 12 is retained in the plug shell 11 by means of interengaging castellations on the insert assembly and the plug shell. For this purpose. there are circumferentially extending lugs 18 that project outwardly from the periphery of the rearward disk 15, as seen in FIG. 4. In the embodiment illustrated. there are five of the lugs 18. The circumferential surface 20 from which the lugs 18 project is substantially complemen tary to the inner surface 21 of the plug shell 11. The slots 22 are made sufficiently wide to permit the insert assembly 12 to be introduced into the plug shell 11 by being slid inwardly from the forward end 23 of the plug shell, with the lugs 18 passing through the slots 22. The insert assembly 12 is moved into the plug shell until the rearward radial edges 25 of the lugs 18 are brought into engagement with an annular shoulder 26 at the rear ward portion of the plug shell.

Circumferential slots 27 are formed at the rearward portion of the inner surface 21 of the plug shell I1, and are of widths substantially equal to the widths of the lugs 18. This provides circumferentially extending shoulders 28 spaced opposite from the annular shoulder 26 of the plug shell. The shoulders 26 and 28 are spaced apart a distance corresponding to the dimensions of the lugs 18 longitudinally of the insert assembly 12. This allows the insert assembly 12 to be rotated after the rearward edges 25 of the lugs 18 have been brought into engagement with the annular shoulder 26. The rotation of the insert assembly brings the lugs 18 in back of the circumferential shoulders 28 and into the circumferential slots 27. This positions the forward edges 29 of the lugs adjacent the circumferential shoulders 28 so that the radial shoulders 26 and 28 of the plug shell 11 hold the insert assembly 12 against longi tudinal movement relative to the plug shell.

One of the lugs 18 may include a longitudinally forwardly projecting portion 31 having a side edge 32 which is brought into engagement with the side edge 33 of one of the longitudinal slots 22 in the plug shell for thereby limiting the rotational movement of the insert assembly 12 (see FIGS. 4 and 7). when the forward projection is provided, it assures that the insert assembly 12 assumes the proper rotational alignment relative to the plug shell. After being properly positioned in the plug shell 11, the insert assembly is locked in place so as to prevent it from being given reverse rotation. This may be accomplished by bonding the insert assembly to the plug shell.

With the insert assembly positioned in this manner, a rearward sealing element 35 made of a resilient elastomer. such as silicone rubber, is bonded to the rearward radial face of the insert assembly and to the rearward portions of the inner circumferential wall 21 of the plug shell.

The pin contacts 13 are received in spaced parallel openings 38 formed in the insert assembly 12. The openings 38 are continuous from the front to the rear of the insert assembly 12. and are separated from each other so that there is no communication from one opening 38 to the other. The connector is designed so that a large number of the pin contacts 13 may be retained in close adjacency. but. for clarity of illustration.

only a relatively few such contacts are shown in the drawing.

Each opening 38 includes a relatively wide-diameter portion 39 at the rearward end of the plastic disk which, through a frustoconical portion 40, tapers forwardly to a portion 41 of smaller diameter. A plurality of fingers 42 extends radially inwardly and axially forwardly from the portion 41 of the opening 38 into the continuation 43 of the opening 38 in the member 15. This positions the fingers 42 inwardly and radially opposite the circumferential wall of the portion 43 of the opening 38. The fingers 42 are shorter than the section 43 of the opening, so that their forward ends are inward of the forward radial face 44 of the member 15. There are four of the fingers 42 in the example shown, as illus trated in FIG. 8. The fingers 42 are rounded transversely so that collectively they define a generally frustoconical shape with narrow spaces between adjacent fingers. While the plastic member 15 is relatively hard and rigid, the fingers 42 are thin and, therefore, resilient. A radial shoulder is formed by the rearward face 45 of the member 14 where the diameter of the opening decreases at portion 46. [n the gasket member 16, the opening has a relatively wide-diameter portion 47 at the rearward end and a smaller-diameter portion 48 at the forward end.

An opening 49 in the rearward sealing member 35 communicates with each of the openings 38.

The pin contacts 13 may be of conventional construction, inclulding hollow, longitudinally elongated barrel portions 50 at their rearwards ends, which receive the ends of wires 51 from which the insulation has been stripped. The contact barrels 50 are crimped to the wires 51 to form a mechanical and electrical connection. The wires 51 enter the openings 38 through the openings 49 in the rearward member 35, being engaged by annular sealing beads 52 formed on the circumference of the opening 49.

Forwardly of the barrel portion 50, each contact 13 includes a part 53 of enlarged diameter which defines forward and rearward shoulders 54 and 55, respectively. Beyond the forward shoulder 54, the contact narrows to a projecting pin portion 56 that is adapted to enter the socket contact. When installed in the opening 38, the forward shoulder 54 of the contact is adjacent the rearwardly facing shoulder defined by the rearward face 45 of the insert 14, which thereby prevents forward movement of the contact 13.

In this manner, the contact is positioned within the insert assembly and securely retained. With the use of the integral fingers 42, it is unnecessary to provide any auxiliary metal clip for retaining the contact, as in conventional connector construction. This simplifies the manufacture of the connector and lowers its cost. The danger of an improperly installed retainer clip is obviated. With the fingers 42 being entirely received in the section 43 of the opening 38, which locates them rearwardly of the forward face 44 of the disk 15, the bonding together of the inserts l4 and 15 will not adversely affect the fingers. In other words, the fingers are remote from the bond line so that any excess bonding material squeezed out at the joint will not interfere with the movement of the fingers.

As best seen in the enlarged illustration of FIG. 10, the fingers 42 are thicker in cross section at their forward ends than they are at their points of attachment to the insert [5, being tapered gradually in thickness to the rear. Also, each finger has a substantially radial for ward end surface 57 which connects at a right angle to an inner end surface 58, which is a cylindrical segment generally complementary to the barrel 50 of the contact 13. When the finger 42 engages the contact 13, the radial end surface 57 fits behind the rearward shoulder 55 of the contact, while the inner end surface 58 of the finger rests upon the barrel 50 adjacent the shoulder 55.

The rearward transverse shoulder 55 of the contact 13 does not fall within a radial plane. Instead, it is inclined toward the forward end of the contact. Consequently, the shoulder 55 is undercut, being defined by a frustum of a cone. Desirable results are achieved when the shoulder 55 is inclined at around 12 relative to a radial plane. When the contact 13 is subjected to a force pushing it toward the rear, the undercut shoulder configuration and the inner finger surfaces 58 contribute greatly to the amount of force which can be absorbed before the retention fingers 42 will fail.

With the arrangement of this invention, the fingers 42, loaded as columns, receive the forces on them near the neutral centers of the columns, minimizing the tendency to buckle. The plastic of the fingers 42, being softer than the metal of the contact 13, becomes dis torted where it engages the radially outer portion of the shoulder 55, as illustrated in particular in the enlarged view of FIG. 12. This has the effect of embedding the shoulder in the outer ends of the plastic fingers 42, stabilizing the finger ends. This increases the column strength of the fingers 42 because a column can withstand more loading if its ends are stabilized.

An additional stabilizing effect is realized because of the arcuate inner surfaces 58 of the fingers 42 substantially complementarily engaging the periphery of the barrel 50 of the contact adjacent the base of the shoulder 55. This helps to anchor the free ends of the fingers. The inclined configuration of the shoulder 55 results in a force component on the fingers 42 helping to hold the surfaces 58 toghtly against the circumference of the barrel 50 to enhance the column stabilizing effect.

The greater wall thickness of the fingers at their outer ends adds to their strength in shear and in bending. The bending strength resists the buckling of the fingers under load.

Another advantage comes from the fact that the inner corner 59 of the finger 42, between the end sur face 57 and the inner surface 58, becomes spaced rearwardly from the fillet 60, which necessarily is formed between the shoulder 55 and the barrel 50 when the contact 13 is machined. When there is a straight radial shoulder, the inner corners of the retention fingers will engage the fillet at the base of the shoulder. This deflects the fingers outwardly, thereby tending to cam the fingers out of engagement with the shoulder. The undercut shoulder 55 permits the finger to clear the fillet 60 without requiring a recess in the finger and without sacrifice in the strength of the fingers.

The insert assembly 61 for the receptacle 10 includes a plastic disk 62 that is similar to the member 15. To it is bonded or otherwise suitably secured a forward cover disk 63. The members 62 and 63 also may be made of Astrel 360 plastic. Outwardly projecting lugs 64 on the disk 62 correspond to the lugs 18 on the member 15. The lugs 64 secure the insert assembly 6] to the receptacle shell 65 in the same way that the lugs 18 attach the insert assembly 12 in the plug shell 11.

The insert assembly 61 is introduced into the receptacle shell 65 by passing the lugs 64 through axial grooves in the inner surface of the receptacle shell 65, whereupon subsequent rotation of the insert assembly 61 places the lugs 64 between opposed forward and rearward shoulders 66 and 67, respectively, in the receptacle shell. This holds the disk 62 and the cover element 63 within the receptaclev The socket contacts 68 are retained in continuous separate openings 69 in the insert assembly of the receptacle, positioned against axial rearward movement by integral fingers 70 that project forwardly and inwardly from the insert disk 62. A shoulder 71 on the insert member 63, where the opening 69 reduces in width, is adjacent the forward end of the contact 68 and precludes forward movement of the contact. The fingers 70 are engageable with the rearward edge of the annular enlargement 72 on the socket contact. A wire 73 extends inwardly through an opening 74 in the rearward sealing member 75 of the receptacle for each of the socket contacts 68. The end portions of the wires 73 are stripped of insulation and connected by crimping to the rearward barrel ends 76 of the socket contacts 68. When the forward ends 77 of the socket contacts receive the projecting pin portions 56 of the pin contacts 13 upon the mating of the connector, circuits are completed between the wires 51 and 73.

A rounded annular bead 78 projects outwardly from the forward radial face 79 of the cover disk 63 of the receptacle insert around each of the openings 69. The bead 78 is engaged by the flat forward face 80 of the gasket 16 of the plug 9 when the connector is in the assembled position. Consequently, the bead 78 displaces the resilient material of the gasket 16 and an efficient moisture seal is produced. This type of seal does not rely upon the entry of a projecting part of the resilient elastomer into a recess in the hard plastic of the mating part as in some prior-art designs. Unlike the previous designs, swelling of the gasket 16 from attack of fluids will not appreciably interfere with the mating of the connector so that the axial force required will not vary significantly under those conditions.

The mechanism for securing the plug and receptacle together in the mated position includes a coupling ring 81 that circumscribes the plug shell 11. The rearward end of the coupling ring includes a radially inwardly extending flange 82 in back of a rearwardly facing shoulder 83 on the plug shell. A snap ring 84 fits in an annular recess 85 in the intermediate portion of the inner circumferential wall of the coupling ring 81. The snap ring 84 is positioned in front of a forwardly facing ra dial shoulder 86 on the plug shell 11, cooperating with the flange 82 in retaining the coupling ring 81 on the plug shell 11. This allows the coupling ring 81 to rotate relative to the plug shell 11, but relative axial movement is prevented.

Intermediate the snap ring 84 and the flange 82, the coupling ring 81 is provided with three short, arcuate, longitudinally extending recesses 87 in its inner surface 88 (see FIGS. 2 and 5). These recesses are adapted to receive the outer rounded portion 89 of a leaf spring 90. The latter member has normally straight legs 91 terminating in an inwardly bent end 92 which is received within a radial opening 93 in the periphery of the plug shell. This holds the spring 90 to the plug shell 11. Adjacent the legs 91 of the spring 90 are flat chordal surfaces 94 which provide a clearance for permitting flexure of the spring 90.

By this construction, the coupling ring 81 can be rotated relative to the plug shell 11, but there is a detent action tending to prevent relative rotation when the portion 89 of the spring enters a recess 87. This retaining force may be overcome by applying adequate torque to the coupling ring to cam the rounded spring portion 89 out of the recess 87, compressing the spring inwardly and allowing the spring portion 89 to slide along the circumferential surface 88 of the coupling ring intermediate the recesses 87.

Forwardly of the snap ring 84, three bayonet grooves 95 are formed in the inner circumferential surface 88 of the coupling ring. Each groove 95 includes a wide entrance opening 96 at the forward end 97 of the coupling ring, from which there extends an inclined portion 98 of the groove, leading to a circumferential inner part 99 of the groove. The axis of the latter portion of the bayonet groove 95, as best seen in FIGS. 2 and 14, falls entirely within a radial plane as there is no recess for the bayonet pin at the inner end 100 of the groove.

The receptacle shell 65 includes a forward portion 101 of enlarged diameter which provides a clearance around the insert assembly 61. At the end of the forward portion 101 of the receptacle shell are three radially outwardly projecting bayonet pins 102.

When the electrical connector is to be mated, the forward end portion 103 of the plug shell 11 enters the forward portion 101 of the receptacle shell 65, fitting in the clearance space around the insert assembly 61 of the receptacle. Keys 104 on the plug shell fit in keyways 105 in the receptacle shell, assuring the proper rotational alignment of the plug and receptacle. With the keys in the keyways, the detent spring, when in a recess 87 in the coupling ring, positions the coupling ring so that the entrances 96 of the bayonet grooves 95 are aligned with the bayonet pins 102. Therefore, the bayonet pins 102 are brought to the entrances 96 of the bayonet grooves 95 in the coupling ring 81 as the plug and receptacle are advanced axially toward each other. Subsequent rotation of the coupling ring 81 moves the bayonet pins 102 through the inclined portions 98 of the grooves 95 and into the circumferential portions 99, drawing the plug and receptacle into the fully mated position. The coupling ring 81 is turned until the pins 102 are adjacent the inner ends 100 of the grooves 95, which occurs as the outer portion 89 of the spring 90 enters a detent recess 87 in the coupling ring.

A positive stop is provided in one of the bayonet grooves to prevent rotation of the coupling ring 81 past the detent position when the connector is mated. This is accomplished by bending inwardly a small section 106 of the circumferential wall of the coupling ring, presenting an abutment surface 107 in the bayonet groove where it can be contacted by the bayonet pin at the termination of the rotation of the coupling ring 81 (see FIG. 6). This location corresponds to the positioning of the outer portion 89 of the detent spring 90 in a detent receptacle 87. An opening 108 is formed in the wall of the coupling ring adjacent the stop 107, while two additional openings 109 in the coupling ring are spaced from the opening 108. This permits visual exterior inspection of the connector when in the mated position to ascertain whether or not the bayonet pins 102 have moved a sufficient distance into the bayonet grooves 95. When the ends of the pins 102 (which may be painted) can be seen through the openings 108 and 109, it is known that the bayonet pins are in the inner portions of the bayonet slots and that the plug and receptavle are coupled properly.

By this arrangement, the plug and receptacle are advanced axially toward each other the maximum distance when the bayonet pins are adjacent the ends 100 of the grooves 95 that receive them. No outward movement occurs as the connection is made, and, when the bayonet pins 102 reach the circumferential portions 99 of the grooves 95, the parts are held in their position of full maximum engagement. Even though subjected to a separating force, no relative movement of the plug and receptacle can take place, so that electrical continuity through the contacts is assured. The bayonet pins 102 are held against the forward sides of the bayonet grooves 95 when separating forces are imposed, while the coupling ring 81 is prevented from movement axially by the engagement of the flange 82 with the rearwardly facing shoulder 83 of the plug shell 11. This provides a solid connection of the parts.

When the connector is in the fully mated position, the forward outer periphery of the forward end of the plug shell 11 engages an annular seal 110. The latter member is held in an annular groove 111 in the receptacle shell 65 by bonding.

In some instances, the snap ring 84 may be provided with forwardly projecting tabs 113 that are brought into engagement with the end of the forward portion 101 of the receptacle shell 65 when the connector is mated (see FIG. 15). This puts a desirable tension on the coupled plug and receptacle, eliminating any clearance in the coupling mechanism. This also makes an electrical connection between the plug shell 11 and the receptacle shell 65.

The plug and receptacle are disconnected by reverse rotation of the coupling ring 81 to free the bayonet pins 102 from the bayonet grooves 95. As this is accomplsihed, the detent spring 90 is forced out of one detent recess 87, and its central part 89 slides along the surface 88 of the coupling ring 81 to the next detent recess 87. In the latter detent position, the bayonet pins 102 have reached the entrances 96 to the grooves 95 and the plug and receptacle may be pulled apart axially.

When the connector is mated, the plug 9 and the receptacle 11 are held together by the reaction of the rearward surfaces of the bayonet pins 102 against the forward edges of the bayonet grooves 95. This causes the forward faces of the inserts in the plug and receptacle to be brought into interengagement and held under compression. When assembled properly, the sealing bead 78 engages and becomes embedded in the forward face 80 of the resilient insert 16 around the mating pin and socket contacts. It is important that the bead 78 of the forward cover disk 63 and the forward face 80 of the insert 16 assume the proper relative position when the connector is mated. If they are advanced toward each other an inadequate distance, the bead 78 will not bear against the gasket disk with sufficient force to form a seal. Too much movement of one insert toward the other will cause overcompression at the mating connector surfaces, making it difficult to mate the plug and receptacle. While some variation is not harmful, manufacturing tolerances can build up so that either objectionable condition can exist.

In conventional connector design, where there is a spring in the coupling mechanism, dimensinonal variations of this sort are not important because the movement permitted by the spring will allow for tolerances and keep the mating faces under proper compression. with the present invention, however, there is no spring in the coupling mechanism, and tolerance buildup requires a different solution. This is accomplished by controlling the positions of the working surfaces of the bayonet grooves and the bayonet pins relative to the forward surfaces of their respective insert assemblies. Each is controlled separately to a predetermined dimensional range.

For the coupling ring 81, tolerance control is effected by menans of a spacer washer 115 which fits between the abutments defined by the rearward flange 82 of the coupling ring 81 and the shoulder 83 on the shell 11 (see FIGS. 16-20). By selecting a spacer washer 115 of proper axial dimension, the distance A (indicated in FIG. 18) between the forward edge 116 of the bayonet groove and the forward face 80 of the gasket insert 16 can be held within acceptable limits. Normally, in a carefully manufactured connector, the distance A can be controlled adequately by having available only a limited number of sizes of the spacer washers 115. Three such washers, such as the washers 1150, 1151a and C shown in FIG. 20, will suffice.

In the assembly procedure, the coupling ring 81 is positioned on the shell 11 with one thickness of washer, selected by estimation or arbitrarily, positioned between the flange 82 and the shoulder 63. The distance A then is measured. Obviously, if the selected washer causes the distance A to fall within the proper range, nothing more need be done. However, if the distance A is over or under the specified range, the originally chosen washer is replaced by one of a thickness such that the distance a will be brought to within proper limits. Simple addition orr subtraction will establish the choice of spacer washer. a thicker washer will move the forward edge 116 of the groove 95 closer to the surface 80. and a thinner washer will increase the distance between the forward edge 116 and the suyrface 80.

In the receptacle 10, it is necessary to maintain the correct distance B between the rearward working sur faces of the bayonet pins 102 and the forward edge of the bead 78 (see FIG. 21). This is accomplished by providing bayonet pins 102 with different diameters at their exposed portions, permitting selection of a bayonet pin of proper size. This may be a choice from among two pins, such as the pins 102a and l02b illustrated in FIG. 22. In each instance, the shank portion 117 is the same and can fit complementarily in the opening 118 in the shell 65. However, the enlarged outer parts 119a and 119b, which are adapted to fit in the bayonet groove 95, are of different diameters.

In selecting the proper bayonet pin, the distance C is measured from the rearward edge of the opening 118 in the receptacle shell 65 to the forward edge of the bead 78. With this distance being known, it is possible then to select the bayonet pin having its outer part 1190 or 11% dimensioned so as to result in a distance B within accepted limits. Obviously, when the distance C is at a minimum, the bayonet pin with the smaller outer end 119a is selected, while larger distances C require the bayonet pin having end 11%.

Because the opening 118 and the forward face 79 of the receptacle insert are radial with respect to the connector, the distance C may be found by first inserting a rod 120 through the opening. The rod 120 is extended inwardly parallel to the forward face 79 of the insert 63. A measurement can be made without difficulty between the rearward edge ofthe rod 120 and the forward edge of the sealing bead 78. This is the same dimension as that between the rearward edge of the opening 118 and the bead 78, which is the distance C4 The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

I claim:

1. In combination with a first body and a second body, an arrangement for coupling said first body to said second body comprising an annular member circumscribing said first body,

means retaining said annular member to said first body so that said annular member is rotatable relative to said first body and substantially axially fixed relative to said first body including a first radially extending shoulder on said first body,

a second radially extending shoulder on said first body,

said snap ring including at least one resilient tab extending outwardly therefrom for engaging said second body and exerting a resilient force thereon when said first and second bodies are coupled and providing an electrical connection to said second body, said annular member having an inner circumferential surface having at least one groove therein, said groove having an opening at one end of said annular member providing an entrance thereto, said groove having an inner portion and an inclined portion interconnecting said entrance and said inner portion of said groove, said inner portion of said groove being circumferential relative to said annular member, the longitudinal axis of said inner portion falling in a plane that is substantially radial relative to said annular member, a pin on said second body projecting outwardly therefrom, said pin being adapted to enter said groove and to be transmitted through said entrance and said inclined portion to said inner portion of said groove upon rotation of said annular member relative to said first body and said second body, said second body having an annular portion adapted to circumseribe a part of said first body intermediate said first body and said annular member when said pin so enters said groove, and resilient detent means engaging said first body and said annular member to resist rotation of said annular member relative to said first body when said pin is in said inner portion of said groove. 

1. In combination with a first body and a second body, an arrangement for coupling said first body to said second body comprising an annular member circumscribing said first body, means retaining said annular member to said first body so that said annular member is rotatable relative to said first body and substantially axially fixed relative to said first body including a first radially extending shoulder on said first body, a second radially extending shoulder on said first body, an inwardly directed flange on said annular member adjacent said first shoulder for preventing movement of said annular member relative to said first body in one direction, said annular member having an internal annular recess, and a snap ring received in said recess and extending therefrom to a position of adjacency with said second shoulder so that said snap ring engages said first body and said annular member for preventing movement of said annular member relative to said first body in the opposite direction, said snap ring including at least one resilient tab extending outwardly therefrom for engaging said second body and exerting a resilient force thereon when said first and second bodies are coupled and providing an electrical connection to said second body, said annular member having an inner circumferential surface having at least one groove therein, said groove having an opening at one end of said annular member providing an entrance thereto, said groove having an inner portion and an inclined portion interconnecting said entrance and said inner portion of said groove, said inner portion of said groove being circumferential relative to said annular member, the longitudinal axis of said inner portion falling in a plane that is substantially radial relative to said annular member, a pin on said second body projecting outwardly therefrom, said pin being adapted to enter said groove and to be transmitted through said entrance and said inclined portion to said inner portion of said groove upon rotation of said annular member relative to said first body and said second body, said second body having an annular portion adapted to circumscribe a part of said first body intermediate said first body and said annular member when said pin so enters said groove, and resilient detent means engaging said first body and said annular member to resist rotation of said annular member relative to said first body when said pin is in said inner portion of said groove. 